mayfly
Epic Member
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The pedal prototyper reminded me of a tube amp prototyper that I had built about 10 years ago. I had forgotten it until that thread, but I just dug it out to show you all.
Do NOT attempt to build anything like this unless you really know what you are doing. Doing otherwise will burn your neighbor's house down, kill your cat/dog, and fry your private bits off
With that out of the way, here it is. There are three separate boxes for maximum reconfigurability: the power supply, pre-amp, and the power amp:
The power supply uses a hammond transformer and has a 300VDC B+ supply, a -56VDC bias supply, 6VAC heater supply, and a 6VDC regulated heater supply. The latter I threw in to see what difference it really makes under certain circumstances. The dust on this unit really shows how long it's been since I've used it!
Here's the inside. Plenty of decoupling (those are 100uf 400V caps), and a big fuse block. Those who know tube amps know that you don't want to dick around with safety - so those are fast blow fuses on each leg of every supply.
Here's the pre-amp. This was the circuit that went through the most experiments. It's a two channel pre, with a black face type clean channel, and a mesa-style lead channel. The main thing that I learned from this unit was I didn't like Mesa-style preamps :icon_biggrin:
and here's the inside - again plenty of decoupling. I kinda went overboard, but I didn't want to be driven crazy with 60Hz hum
The power amp went though several changes as well. Here it is configured for 6V6 tubes, fixed bias. There are switches for flipping it into triode mode, and the pots are for master volume and feedback loop experiments. It has also seen cathode bias, 6L6 and EL34 Tubes. From this unit I realized that I was not a fan of fixed bias amps :icon_thumright:
Here's the outside:
and here's the inside:
So, where did all that experimentation lead? To these things:
This is an AC30 style amp, with top boost channel, normal channel, and a EL84 based output stage with cathode bias, master volume, and no feedback loop. This is a 15 watt version.
I made several of these in both 30 and 15 watt versions.
Do NOT attempt to build anything like this unless you really know what you are doing. Doing otherwise will burn your neighbor's house down, kill your cat/dog, and fry your private bits off
With that out of the way, here it is. There are three separate boxes for maximum reconfigurability: the power supply, pre-amp, and the power amp:
![n527102111_1688020_9934.jpg](/proxy.php?image=http%3A%2F%2Fphotos-e.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688020_9934.jpg&hash=d1605f801c053ef3b58616767ba55eae)
The power supply uses a hammond transformer and has a 300VDC B+ supply, a -56VDC bias supply, 6VAC heater supply, and a 6VDC regulated heater supply. The latter I threw in to see what difference it really makes under certain circumstances. The dust on this unit really shows how long it's been since I've used it!
![n527102111_1688023_846.jpg](/proxy.php?image=http%3A%2F%2Fphotos-h.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688023_846.jpg&hash=b923d37ad14b3a854e218e29bfb1e6e3)
Here's the inside. Plenty of decoupling (those are 100uf 400V caps), and a big fuse block. Those who know tube amps know that you don't want to dick around with safety - so those are fast blow fuses on each leg of every supply.
![n527102111_1688021_251.jpg](/proxy.php?image=http%3A%2F%2Fphotos-f.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688021_251.jpg&hash=93228176332d10e7b397fe9f4e61b1c6)
Here's the pre-amp. This was the circuit that went through the most experiments. It's a two channel pre, with a black face type clean channel, and a mesa-style lead channel. The main thing that I learned from this unit was I didn't like Mesa-style preamps :icon_biggrin:
![n527102111_1688026_1738.jpg](/proxy.php?image=http%3A%2F%2Fphotos-c.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688026_1738.jpg&hash=eebe8b9cddfe2d4d1396584ffbf4d33e)
and here's the inside - again plenty of decoupling. I kinda went overboard, but I didn't want to be driven crazy with 60Hz hum
![n527102111_1688025_1450.jpg](/proxy.php?image=http%3A%2F%2Fphotos-b.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688025_1450.jpg&hash=18379bda5eaad29255bdad5261c18d88)
The power amp went though several changes as well. Here it is configured for 6V6 tubes, fixed bias. There are switches for flipping it into triode mode, and the pots are for master volume and feedback loop experiments. It has also seen cathode bias, 6L6 and EL34 Tubes. From this unit I realized that I was not a fan of fixed bias amps :icon_thumright:
Here's the outside:
![n527102111_1688027_2038.jpg](/proxy.php?image=http%3A%2F%2Fphotos-d.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688027_2038.jpg&hash=14e1a8d2eba89f24b90d1e4de4c8c145)
and here's the inside:
![n527102111_1688028_2356.jpg](/proxy.php?image=http%3A%2F%2Fphotos-e.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688028_2356.jpg&hash=2600cfcf6b3f54849024dab52f4b3dcf)
So, where did all that experimentation lead? To these things:
![n527102111_1688031_3304.jpg](/proxy.php?image=http%3A%2F%2Fphotos-h.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688031_3304.jpg&hash=150803e9f2bbaf06710e88ca43f15a41)
![n527102111_1688034_3608.jpg](/proxy.php?image=http%3A%2F%2Fphotos-c.ak.fbcdn.net%2Fphotos-ak-snc1%2Fv761%2F40%2F87%2F527102111%2Fn527102111_1688034_3608.jpg&hash=a89aab394fee4a8d058c43c2934a1ac2)
This is an AC30 style amp, with top boost channel, normal channel, and a EL84 based output stage with cathode bias, master volume, and no feedback loop. This is a 15 watt version.
I made several of these in both 30 and 15 watt versions.